1. Field of the Invention
The present invention relates to a magnetic levitation vehicle system in which a vehicle is supported in a noncontact state, guided and driven by magnetic attraction forces interacting between a supporting electromagnet, a guide electromagnet and a magnetic rail.
2. Description of the Prior Art
FIG. 5 is a sectional view of a conventional magnetic-levitation vehicle and a magnetic rail. Supporting electromagnets 5 with their magnetic poles directed upwardly and guide electromagnets 4 with their magnetic poles directed horizontally are mounted on a chassis 3 of a vehicle 1 in symmetrical relationship with the centerline of the chassis 3. On either side of a track 8, magnetic rails 6 are mounted on both sides of a cross beam 7 in such a way that rail surfaces are directed downwardly and transversely, respectively. When the currents respectively made to flow through the electromagnets 4 and 5 are suitably controlled, the chassis 3 is a levitated and guided in noncontact state while the electromagnets 4 and 5 maintain an opposing and spaced-apart relationship with the magnetic rails 6, respectively. Thrust imparted to the vehicle 1 is produced by electromagnetic energy interacting between armatures 9 of linear induction motors mounted on the chassis 3 and secondary rails 10 of the track 8. The secondary rail 10 of a linear induction motor is used which in general include a steel sheet whose upper surface is laminated or otherwise joined with a sheet of electrically conductive material such as aluminum.
The conventional liner induction motor for a magnetic-levitation vehicle or car involves a cost for attaching the secondary rail 10, such as a sheet of copper, aluminum or the like, over the surface of the magnetic rail 6 consisting of a lamination of sheets of steel.
Furthermore, the conventional linear induction motor requires costs of maintenance for eliminating electrolytic corrosion between steel and a secondary conductor. Various methods are available for attaching the secondary conductor to steel, such as the explosive welding method for welding a sheet of aluminum to steel, and the method for joining them with screws. The explosive welding method is expensive, while the screw joint method has a problem in that it is difficult to prevent adverse effects caused by icing during winter. A further problem resides in the fact that the armatures 9 of the linear induction motors are mounted on the side of the vehicle 1, and therefore the weight of the vehicle is increased accordingly. The increase in weight of the vehicle not only results in increase in the cost of manufacture and maintenance but also causes increase in the cost of construction of the track.
Furthermore, like the Transrapid TR06 system developed in West Germany, in the case where linear synthronized motors (LSM), of the type in which armatures are disposed on the ground or track and supporting electromagnets mounted on a vehicle are used as field magnets, product thrust, the supporting electromagnets also function as field magnets of the LSM so that the vehicle can be made light in weight, but primary windings must be mounted on the whole track, causing the cost of construction for installation on the ground to become expensive. Moreover, even when excitation sections are switched over, an armature portion in excess of the length of the vehicle must be always excited, resulting in great energy losses. On the other hand, there have been devised and demonstrated a method in which, unlike the system as shown in FIG. 5, armatures of linear induction motors are disposed on the ground and secondary circuits are mounted on the side of a vehicle. This method can make the vehicle light in weight, but as in the case of TR06 system, the costs of construction for installation on the ground are expensive. Furthermore, even when exciting sections are switched over, an armature portion in excess of the length of the vehicle must be always excited, resulting in great energy losses.